Cam pipe couplings are usually used to detachably couple a flexible hose to a solid walled pipe line. An end portion of the solid walled pipe line usually is provided with a valve before terminating in the female portion of the cam coupling. It is the female portion of the cam coupling which contains diametrically opposite cams which are moved by lever arms, or “ears” to releasably lock the male portion therein.
Cam couplings are frequently used to removably couple a flexible hose to a storage tank or to a smaller tank on a truck. In the oil industry it is critical that the couplings stay coupled when oil is being pumped through a flexible hose which is attached to the male end portion of the pipe coupling. A spill even of a few gallons of oil must be reported and typically costs thousands of dollars to clean up.
After the flexible hose is removed from the female portion of the coupling (having the lever arms attached thereto) it is common practice to insert a similar mating male portion of the coupling therein which is either plugged or capped. This is done as an added safeguard against the valve either opening or leaking.
Devices are available to lock the lever arms of a cam coupler in a closed position.